Exemplary embodiments described in this document relate to a light emitting device. For example, some embodiments of the present document relate to a light emitting device that has high current spreading efficiency to provide good properties in terms of luminous efficacy and reliability.
Generally, a light emitting device such as a light emitting diode includes an n-type semiconductor layer supplying electrons, a p-type semiconductor layer supplying holes, and an active layer interposed between the n-type semiconductor layer and the p-type semiconductor layer. An n-type and a p-type electrode are formed on the n-type semiconductor layer and the p-type semiconductor layer, respectively, to receive electric power from an external power source.
On the other hand, a nitride semiconductor-based p-type semiconductor layer has lower electrical conductivity than the n-type semiconductor layer. As a result, electric current is not efficiently spread in the p-type semiconductor layer, thereby causing current crowding in a certain region of the semiconductor layer. When current crowding occurs in the semiconductor layer, a light emitting diode becomes vulnerable to electrostatic discharge and can suffer from current leakage and efficiency droop. In order to achieve efficient current spreading, a transparent electrode such as an indium tin oxide (ITO) electrode is formed on the p-type semiconductor layer and the p-type electrode is formed on the ITO layer.